Table T2. Significant spectral features used in the four- and three-mineral calculations. The coefficients for the minerals related to each feature and correlation coefficients are also included.
Spectral feature
Calcite
Opal
Smectite
Illite
Constant
Correlation
coefficient
Four-mineral numbers:





1900-nm trough depth
0.2089 0.3017
0.0659 0.875
1400-nm trough depth -0.0924

-0.0478 0.0947 0.792
2330-nm trough depth relative to the 2260-nm peak
-0.0719 0.0252
0.0444 0.663
2330-nm trough depth relative to the 2100-nm peak

0.1166 0.0395 0.1005 0.711
1400-nm trough-1900-nm trough
0.2088 0.1202
0.0426 0.869
2100-nm peak-1850-nm peak
-0.0749

0.0472 0.657
2315-nm peak-2330-nm trough 0.0231
0.0567 0.0489 -0.0135 0.825
Average reflectance 0.4543 0.3812

0.3819 0.916
Three-mineral numbers:





1900-nm trough depth -0.2241
0.0912
0.2783 0.865
1400-nm trough depth -0.1023
-0.0149
0.1032 0.793
2330-nm trough depth relative to the 2260-nm peak -0.0272 -0.0967

0.0697 0.660
2330-nm trough depth relative to the 2100-nm peak

0.1167
0.1004 0.712
1400-nm trough-1900-nm trough -0.2049
-0.0877
0.2502 0.839
2100-nm peak-1850-nm peak
-0.0768

0.0481 0.651
2315-nm peak-2330-nm trough 0.0231
0.0567
-0.0135 0.798
Average reflectance 0.0858
-0.3515
0.7501 0.890